Final answer:
The presumption that Huck's father killed him would stem from his father's violent history and Huck's mysterious disappearance.
Step-by-step explanation:
The main reason people might think Huck's father killed him is a combination of Huck's father's past violent behavior, the disappearance of Huck, and any potential evidence or rumors that could lead to that suspicion.
In literature, particularly in novels with themes of tension, misunderstanding, or conflict, a character's previous actions or reputation often inform other characters' and even readers' expectations about their behavior.
Huckleberry Finn, the character in question, fakes his own death to escape his abusive father in Mark Twain's novel 'The Adventures of Huckleberry Finn'.
The father's known violent predisposition coupled with Huck's sudden disappearance might lead to the presumption of murder by those not aware of the truth of Huck's escape.